Subaqueous sound-producing device



April 8, 1930.. Abuy BolsQRx-:YMOND ET AL 1,753,368

suaAQuEous soUND PRoDUcING DEVICE Filed July 17, 1'9 2o 2 sheets-sheet 1 8, 1930. A. DU Bols-REYMOND ET AL 33539368 I SUBAQUEOUS SOUND PRODUCING DEVICE 2 Sheets-Sheet 2 Filed July 17. 1920 Patented Apr. 8,'1930 i UNITED STATI-:As

PATET* or-Flce ALARD DU BOIS-REYMOND, 0F PLON, NEAR KIEL, AND WILHELM RUDOLPH, OF KIEL,

GERMANY, ASSIGNOBS T FIRM SIGNAL GESELLSCHAFT M. B. H., 0F KIEL, GER- MANY SUBAQUEOIIIS `VS DUN'ID-IEROID'UCIN G :DEVICEV Application med-July 17, 1920, Serial No. 397,136, and in Germany September 22, 1919.

This invention relates to sound producers, especially for the purpose of emitting sound Waves under water, which may be excited by strokes imparted to a radiating surface or a particular oscillatory structure coupled with the radiating surface or diaphragm. Sound producers of this kind may be actuated by pneumatic, hydraulic, or electromagnetic means., An advantage of electromagnetically actuated devices is that they permit of the sound producers being placed at any distance away from the source of energy, because the electric power can be supplied easily over very long distances through cables.

The sounding body proper of such sound producers generally has the form of a bell, but it has been proved more advantageous to employ a sounding plate or diaphragm instead of a bell. This plate or diaphragm may be arranged so as to serve as the cover of a casing which contains the striking mechanism. Such an arrangement in combination with pneumatic or electromagnetic actuating means constitutes an extraordinarily tight apparatus which is devoid of moving parts passed through sealing gaskets and whose acoustic properties are easy to understand and to iniiuence because a specially adapted radiating member is used for setting up and emitting the sound. But the blows delivered against such a sound emitting plate must, as has been repeatedly pointed out, be directed as nearly as possible at right angles to the -largest plane ofv the plate and towards its centre, or at least towards points which are situated symmetrically with respect to its axis. The rules governing the direction of the blows are also practically the same in cases in which the vibrating plate or diaphragm acts only as a radiating member and has a separate vibratory structure associatedwith it which receives the blows and, as it were, impresses its vibrations on the radiating member. This applies particularly in cases where the vibratory structure is made up of several masses or weights connected to each other by elastic members and arranged to oscillatein a direction at right angles to the diaphragm.

In constructing striking "mechanisms for hammer sound producers a fundamental difficulty is encountered. 'IAo cause the vibratory structure or the diaphragm to oscillate it must According to the laws of elasticity the amounts of energy that 'exist in the striking and struck bodies or masses after the delivery of the blow depend first of all upon the relative sizes of these masses. But the striking body is alsq subject to the laws of mechanical design. If the striking body is impelled byelectromagnetic means the armature of the electromagnet may either be accelerated by the power of magnetic attraction, or the armature may be moved in opposition to a counter-force such as the tension of a spring, which, after the interruption of the current, hurls the armature against the sound emit ting plate. In both cases the armature is a striking weight on the one hand, and a part of the electromagnet on the other, and to adapt it for both of these purposes it is necessary to proceed along lines which are frequently antagonistic. The conditions underlying other methods of operating the striking member are similar.

To overcome this dificulty in hammer sound producers of the kind herein described the invention contemplates a special striking body which is freed during striking from all functions in the striking mechanism but that of delivering the blow. Hence in cases where the driving means is an electromagnet a special striking body is provided in accordance with the invention in addition to the armature, and the arrangement is such that when the blow is struck the striking body which is impelled by the armature performs the striking function alone, i. e. the mass of the armature itself is eliminated. A kind of double electromagnetic actuation is also feasible, to obtain which the armature of a primary magnet is constructed in the form of a secondary magnet whose armature 1s 1n turn constructed in the form of a striking body or hammer.. The invention renders it possible to construct the parts of the striking mechanism and lthe separable striking body so that the size of each of these parts corresponds to the laws governing it so that for example the such that the hammer is liberate armature of the primary lelectromagnet,

which, in horder to be capable of performing its work, requires a large` amount of iron, cany be made large and heavy, whilst the striking body 4itself can be made proportionately small. ,l g L In reducing the invention to practice devices may be evolved in which the hammer is raised (directly or through the medium of levers whichincrease its stroke) in opposition to a special force, such as that of a spring or gravity, whereupon the connection between the raising mechanism and the striking jbody is broken and the latter is left to be accelerated by the said special force. If springs or other mechanical elements are used for accelerating the striking body or hammer the preferable arrangement will (generally be Y from these elements the moment the blow is struck and is afterwards recoupled with them. The recoupling of the hammer with the raising mechanism is preferably performed automatically. In devices actuated by an electromagnet the desired effect may be obtained by mechanically coupling the hammer to the armature, by lifting the armature inopposition toa spring by the attractive force of the magnet and, when hammer has been fully raised, by loosening or dissolving the couvplin between the armature and the hammer.

. The ammer is then flung against the vibratory structure and the armature, which drops subseuently when the operating current is cut o is then automatically recoupled with the hammer.

The invention is illustrated in the accom- `panying drawing, in which- F1g. 1 illustrates an electrically driven sound producer with a separate radiating member and vibratory structure and with a striking device composed of an electromagnet armature and a hammer head moving independently of the armature when it delivers its blow.

Fig. 2 represents another electrically driven sound producer with a hammer head.

that is released to strike its blow after it h s been tensioned by the action of the arma e f, the independently stri of the electromagnet.

Fig. 3 shows a pneumatically driven sound producer withl an independently striking ammer head, and y Fig. 4 shows a sound plrpducer in which g hammer is gripped by two curved jaws and then reeased by these jaws after it has been suiciently tensioned.

The ldevice shown in Fig. 1 has a sound radiating plate or diaphragm 1, hereinafter in the claims termed the sound radiator, whose outer surface abuts against the sound propagating medium for instance water. Acoustically coupled to the diaphragm 1 is a vibratory structurev that consists ofv two l, By e Si'oks Oi .fihflme .s 'structure 2', 3, 4 may be 'ca'sedt oscillate and to give, out its acoustic effect to the water weights or masses 2 and 3 interconnected by an intermediate elastic member 4. When this additional vibratory structure is used such as shown in Fig. 1, it is meant to be included in the term sound radiator 1 p v ith@ yilifrtory While lwe ,haver shown in pligs: y sound radiator as a 'diaphragm'with a small mass in the center thereof and without 'the additional vibratory; structure 2, 3, 4 of Fig.

that case theY hammer 'blowis delivered at a point of the sound radiatorv of greatest motion amplitude (namely'atl), Whereas the v1, the latter form is preferable, because in diaphragm. which should perform vamplie tudes of small motion but great power on' account of being in contact with the-water, 1s

.coupled with the structure2, 3, 4 at its point of smallest motion but greatest power amplitude (namely at the lower center of the` large mass 2). This will under water most effectively permit the sound radiator' to'vibrate at its natural frequency and independently of the casing. This independencel is, of course, furtherrendered possible, as is well known in acoustical engineering, by the great mass at the rim of the diaphragm l where it is attached tothe casing.

The hammer 5 is pushed downward to- Y* i Ward the head 0r Weight?) of theI vibrator7 structure by a helical spring 6 whose upper p end presses against the flange 7 and whose lower-end presses against a collar at the bottom end of the hammer 5. A' rubber cushion 8 operates to prevent permanent contact between the hammer and the head 3. The upper end of the casingy contains the field iron 9 of an electromagnet the winding 10 of which is arranged to be connected to is a pin 14which isof such length that the.

air gap-between the straddling member 13 and the end of the pin is somewhat smaller than the travel of the armature 11.

When current is sent through the winding 10 `of the electromagnet the armature 11 is drawn upwards, and as the link parallelogram 12, 12 lacts in the position shown like an inflexible chain it carries the hammer 5 up v,with it and tensions the spring 6. But as soon as the straddling member 13 engages fcoil 21.

the pin 14 its elbow collapses and the link parallelogram is permitted to stretch so that the hammer 5 is propelled downwards and strikes the head 3-of the vibratory structure.

The operating current is now cut 0H by suitable means not shown here andthe armature 11 then drops of its own weight into its normal position shown, thus causing the straddling member 13 to unfold itself and to swing upwards beyond its position of maximum straddle into the normal stretching position shown in the drawing-and in which the normal coupling between Vthe armature and the hammer is restored. This slight upward swing of the center of straddling member 13 after it has been fully stretched is due to the slight elasticity of the link system and to the upward momentum of this center. It will easily be understood that when armature 1l drops and thus stretchesmember 13, the center of the latter is violently impelled upwards and has not lost its momentum, which tends to carry the center past the center line of the toggle joint, at the time when armature 11 is again attracted. Thus the tendency to stretch straddling member 13 is immediately replaced by the tendency to collapse it upwardly as far as the center joint will allow, which thereby restores the toggle joint in straddled position. The described action is repeated at each excitation of the magnet. The described link parallelogram may be replaced by any other suitable automatically releasing coupling means such as a ratchet and pawl mechanism between the magnet armature and thehammer without changing the essential features of the sound producer.

In Fig. 2 an electromagnetically actuated hammer-stroke sound `radiator is shown which differs from the device of Fig. 1 in so far as the diaphragm itself instead of an intermediate vibratory structure is struck and that the coupling between the armature of' the magnet and the hammer is effected by a secondary electromagnet.

The sound radiating diaphragm 15 is attached by a flange to the casing and is Weighted at the middle by a thickened portion 16 separated by a short gap from the hammer or ram 17. The latter has broad shoulders at its upper end 20 and extends almost up to armature 18 of the primary or operating magnet 19. The lower part of' the armature 18 is constructed in the form of a secondary electromagnet whose armature is t-he upper part 20 of the hammer. The secondary electromagnet, i. e. the armature of the primary electromagnet, has embedded, in it a The eld iron 22 of the primary magnet 19 contains a coil 23. The coils 21 and. 23 may-be connected in parallel or in series to a suitable current source such as a continuous current dynamo -not shown here. The hammer 17 is surrounded by a strong helical spring 27 whose ends press against the flanges 24 and 25 respectively. The shoulders of the hammer rest upon a ring of small springs 26 which are arranged in an annular groove of the shoulder portion. When the current is switched on, the hammer 17, 20 is first attracted by the armature 18 so as to establish a rigid connection between these two parts. Then the armature 18 and the hammer 17, 20 are pulled upwards into the field of the primary electromagnet 22, 23 so that the spring 27 is compressed. On the subsequent deenergization of the magnet 22, 23 the spring 27 first acts upon the two separating parts 18 and 17, 20. But as the coil 21 is deenergized at the same time as the coil 23, and the large mass of the armature 18 offers greater opposition to the accelerating force of the spring 27 than the hammer 17 20, this lat-ter is pulled away from the armature 18 and is flung alone against the diaphragm. The descending hammer compresses the springs 26 and after delivering its blow it is restored by these Springs into its normal position shown. The armature 18 also drops (but somewhat slower than the hammer) until it is arrested by the inner ledge 28 of the field iron 22.

The advantage of this arrangement as compared with that of Fig. 1 consists in the absence of mechanical couplings between the hammer and the magnet armature. The circuits of the coils may be arranged in various ways to suit the particular purpose of the device.

In Fig. 3 a modification of a hammer sound producer according to the invention is shown which is adapted to be driven by a compressed fluid.

The actuating member of the striking mechanism is a piston 29 which is lifted by a compressed gas conducted into the cylinder chamber 33 through pipes 30, 30', the hollow valve member 30 (which may be shifted longitudinally in the piston rod 31) and through the ports 32. The port controller 30 protrudes from the upper end of the hollow piston rod 31 and is provided with a cross piece 3()a which slides in grooves 30h in the inner wall of th pipe 30'. The length of the grooves 30h and the hollow port controller 30 are such that when the piston 29 is in the bottom position as illustrated, the holes 32 of the port controller. 30 and of the piston rod 31 register, and the cross piece 30a rests upon the bottom ledges of the grooves 30h. The length of the pipe 30 is such that the cross piece 30a strikes against the flange of the pipe 30 shortly before the piston 29 reaches its uppermost position, so that the upward movement of the hollow ort controller is arrested beforethat of t e piston and the ports 32 in the piston are closed. The piston rod passes through the bottom and top of the cylinder through gas-tight gaskets,

Ilo

and tothe downwardlyextending prolonga tion of the rod a leaf spring 34 is attached which is upheld bya block 35 screwed to the lower end of the rod. An annular leaf spring v36, fixed to the frame of the sender, supports the ram 37 which has an upwardly extending cylinder 38 with an inwardly projecting co1- lar beneath which the leaf spring 34 lies. The ram 37-has a rim 39 and between this rim and the bottom of the piston chamber a strong helical 'spring 40 is inserted.' The radiating plate or diaphragm 41 with its central weight 42 and its strong peripheral flange 43 is screwed fast to the casing of the sound producer and shuts out the sound propagating medium.

The piston 29 is provided'with valves 44 which are automatically pushed open by stops 45 fixed in the cap ofthe piston chamber.

The escaping compressed gas is discharged through the chamber 46 and the outlet 47.

Vhen compressed air is supplied through the pipe t-he piston 29 rises and lifts the ram 37 by means of the leaf spring 34. The' support beneath this spring stiffens this spring, which thus resists downward bendin to a considerable extent so that the ram 3 i may be lifted a considerable distance before the. force of the spiral spring overcomes this resistance of spring 34. The moment this occurs `the ram '37 is separated from the piston. and iung by the spring 40 against the. vradiating plate or diaphragm. The elevation of the piston 29 continues until the valves 44. are opened by the stops 45. .Just before this, the supply of compressed air to the chamber 33 iscut off by the cross piece 3()a striking against the ange `of the pipe register. Compressed air now again'passes into the chamber 33. This keeps the l'valves' 44 closed and lifts the piston again.

The ram 37, in delivering its blow, bends down the annular leaf spring 36, and after this spring recovers and they ram 3 7 has rebounded, the latter is pressed down again by the spring 40 against the leaf spring 36. The piston drops comparatively slowly `behind the ram. Vhen the leaf spring34 attached to its bottom end reaches the inwardly projecting collar 38 at the top of the ram it gives way rather easily and slips down beneath this collar. The apparatusis thenready for a new stroke.

A particular advantage is gained by arranging the ram between the two springs 36 and 40 in so far as vibrations of the ram, that might lead to its chattering against the diaphragm after striking the main blow, are quickly damped.

The simple construction of the apparatus makes it specially suitable for use in connecpivoted at 58, and rods 51 are connected to,

the levers'. When an upward pull is exerted on the rodsin the direction of the arrows by any suitable power device, such as for 'instance magnet armature 11, the jaws are pressed inwards against the hammer 48. Fixed to an upwardly extending member 52 of the hammer is a helical spring 53 whose top end is attached to a stud 54 borne by a cross bar or a transverse wall 55. The levers 50 extend laterally beyond the points of connection with the draught rods51 and their lateral extensions are provided with adjustable stops 56 which co-Operate with fixed stops 57 in the cross bar 55.

`When the rods`51 are pulled upwards the lower ends of the levers 50 swing inwards on the pivots 58 so that the jaws 49 grip the hammer. Since, at the same time, the whole system travels upwards in. opposition `to the helical spring 53, the grip of the jaws on the hammer increases with the growing counterpressure of the spring 53 in such a manner that if no other forces came into action the hammen would compress the spring to its utmost limit. For releasing the hammer from grippers 49 the following means are provided. The pulling bars 51 -are pivotally attached to levers 50 intermediate their common pivot point 58 and their respective free ends .which carry adjustable stops'56. So

long as stops 56 encounter no obstruction,

the lever system rises, gripping the hammer 48 the tighter, the more the spring 53 is tensioned. As soon'as stops 56 abut against fixed stops 57, the free ends of lever 50 are ar- `rested and on further upward pull by bars 51 are compelled to pivot on stops 57, which action opens jaws or grippers 49, so that hammer 48 is released and propelled by spring 53 against the. center 59 of the sound plate. As the lever system subsequently descends (for instance when the electromagnet coil 10 is deenergized) the jaws again`close around hammer 48 and the device is ready for the next stroke. The hammer 48 is guided in its movements by sliding on a guide member 60. It is specifically stated here that in the constructional forms shown in Figs. 2, 3 and j 4 the 'radiating diaphragm or sound radiator may vhave a special vibratory structure associated with it'such as is shown at- 2, 3, 4in

Fig.'1, and that in such event it is included in the term sound radiator.

`We claim: l. A sound producing device comprising a solenoid, a plunger moving within said solenoid, means adapted to grip or release said plunger comprising a pair of substantially semi-circular slices disposed concentrically, a pair of bell crank levers having a common pivot and each supporting respectively one of said shoes, a pair of rods jointed to said bell crank levers at one end and connected to said plunger at the other ends, a i'eciprocable hammer provided with a smooth surface adaptedto'be gripped or released by said shoes and'means actuated by the release of said reciprocable hammer for imparting sound vibrations to the sound medium.

2. A sound producing device comprising an energizing source, a reciprocating hammer provided with a smooth surface adapted to be gripped and means energizing said hammer Vwith said energizing source comprising means heldv by said energizing source for gripping said hammer and means actuated by said hammer for imparting the vibrations of the same to the sound medium, comprising adiaphragm having a large center mass attached thereto, a small mass adapted to be actuated by the vibratory structure and an elastic means connecting said masses.

3. A sound producing device comprising means for exerting a pull in a given direction, a reciprocating hammer provided with a surface adapted to be gripped, and means for operatively connecting said pulling means and said reciprocating hammer, including gripping means exerting a pressure normal to the motion of the pulling means, a sound radiating means and means operated upon the release of the pulling means for forcing said hammer against said radiating means.

4. A sound producing device comprising r, means for exerting a pull in a given direction,

- Na reciprocating hammer provided with a surface adapted to be gripped., and means for operatively connecting said pulling means and said reciprocating hammer, comprising ay pair of'tongs having its legs attached to said first named means and its jaws adapted to exert pressure normal to the motion of said arms for gripping said reciprocating hammer, a sound radiating means and means operated by-the release of the pulling means for forcing said hammer -against said radiating means.

5. A sound producing device comprising means for exerting a pull in a givendirection, a reciprocatingl hammer provided with a sur- `face adapted to be gripped, and means forV operatively connecting said pulling means and said reciprocating hammer, comprising a pair of tongs having its legs attached to said rst named means and its jaws adapted to exert pressure normal to the motion of said arms for gripping said reciprocating hammer, a sound radiating means and a plurality of stops located in the path of the motion of the jaw ends to release said hammer when the jaws have gone beyond a fixed position.

6. A sound producing device comprising electrical means for exertin a pull in a given direction, a reciprocating ammer provided with a surface adapted to be grippedyandl face adapted to be gripped and spring means y positioned to be compressed by the upward movement of the hammer and means operatively connecting said pulling means and said reciprocating hammer comprising a pair of tongs having its legs attached to said first named means and its jaws adapted to exert pressure normal to the motion of said arms for gripping said reciprocating hammer, and a plurality of stops located in the path of the motion of the jaw-ends to release said hammer when the jaws have gone beyond a fixed position whereby said spring means forces 'the hammer in the op osite direction.

' In testimony whereof we have affixed our signatures.

ALARD DU BOIS-REYMOND. WILHELM RUDOLPH. 

